n0nce's Steel Washer Backup jig (customisable)

[n0nce]

n0nce's Steel Washer Backup jig


    Very nicely readable 6mm letters (tape holds washer in place) | Prototypes & final version. Improved letter spacing & tolerances.



This is pretty much how it works

Backup pure material cost: 4€
Requirements: stamps ~20€, jig ~10€
Go big or go home! 30x10.5mm washers!
6mm tall letters
Edit: Any size of washer and stamp is now possible using the openSCAD file I provide for free below. Enjoy!

The idea is inspired from econoalchemist's blog post Securing a Bitcoin seed phrase in stainless-steel washers. and it's very great:

• Materials cost under 5 bucks (€, $, £, it's always the same ballpark). I paid around 3€ for 32 washers and maybe 1€ for the screw and nut.
• No shipping cost since everyone has a hardware store nearby.
• Anonymous since nobody knows what you use basic metal hardware for.
• All stainless steel, quite durable, on par with commercial Bitcoin backup products.
• Greater thickness than some commercial products

Backstory:
After reading the aforementioned blog post, I went to download the file for the jig from blockmic. It can be found in their Thingiverse and they wrote a very good article about it.

But: For one, I wanted to use larger washers. In fact, I think I got the largest that I could find in the first hardware store I walked into. A reason for this is that larger washers are usually also thicker and thus more durable, and the other reason is simply because the stamps I already had were too large for such small washers.

I have 6mm high letters and the stamps are 9x9mm in size.

So I did the natural thing: create a new 3D design from scratch, which is completely parametrized. This allows me to adapt it for anyone with different sized washers and / or stamps! Then did a few iterations, as shown here, and now it's ready to rock!

It's really the most pleasent stamping experience (only did plates without any jig so far), since the stamp is held in place very well, while still being able to slide and of course it's perfectly square. The inner and outer parts are also designed such that there is not much friction when assembling them, but there is no wobble when stamping. So you can actually go back and re-stamp a letter if it didn't come out perfect for example!



PSA: I can achieve much better print quality than what you see in the images, but I am finishing up some old rolls which have taken a lot of humidity so the results don't look as good. Also, I used more perimeters than CryptoCloaks since it makes things more sturdy. Finally, the darker colour you use, the more print lines show (especially when photographed)


An idea to achieve tamper evidence and protection (though we had the discussion if it's even a good idea or not): weld on the nut.
Protection: Not everyone just has an angle grinder.
Evidence: Someone would need to weld it back on which is visible, or redo the backup identically, thus needing a welder AND a 3D printer and all the same supplies that you used. Otherwise the letter size would be different for example.

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[n0nce]

Works in Progress:

• Recreating it another time in OpenSCAD - models are 'coded', parameters can be changed by modifying some variables easily.
• Testing with neodymium magnets which would eliminate the need for tape. Turns out it's too complicated and good tape (can be partly peeled & reused) & hard stamping surface is totally fine.
• Trying double-sided stamping to further reduce cost by half & make backup smaller.

How to get?
To make sure it really works correctly, I'd prefer selling the customized and printed jig.
If I gave the file it could give you headache since I pieced it together quickly and tolerances are quite important when printing it out..
But if you're experienced in modifying designs, printing them or are overseas etc. just send me a DM!
Get the fresh clean source code below and print it yourself or if interested, I can print for you and ship it to a PO box or something. For best privacy, buying or borrowing a cost-effective printer would be recommended.

[NEW!!] OpenSCAD design finalized!
Paste this following code into OpenSCAD (free, open source) and set the parameters to whatever fits your washers and stamps. It's important to measure the stamp's outside size, not the letter height which is usually given on the product page. Then hit F5 and F6 to preview and render the two models. Finally, export the STL file and print it out.

Code:

// n0nce's Steel Washer backup jig
// ---------- configuration ---------- //
washer_dia  = 30;    // set to your washer's diameter (mm)
washer_hole = 10.5; // set to your washer's hole diameter (mm)
washer_h    = 3;     // set to your washer's thickness (mm)
stamp_w     = 8;     // set to your stamp's width (mm)
stamp_d     = 8;     // set to your stamp's depth (mm)

// ---------- code ---------- //
tolerance = 0.25;
// ---------- outer part ---------- //
module roundedcube(xx, yy, height, radius) {
  $fn=60;
  translate([0,0,height/2])
  hull() {
    translate([radius,radius,0])
    cylinder(height,radius,radius,true);

    translate([xx-radius,radius,0])
    cylinder(height,radius,radius,true);

    translate([xx-radius,yy-radius,0])
    cylinder(height,radius,radius,true);

    translate([radius,yy-radius,0])
    cylinder(height,radius,radius,true);
  }
}

module washer() {
  cylinder(h=washer_h, r=washer_dia/2, center=false, $fn=200);
}

module outer() {
  module outer_body() {
    translate([-27, -27, 0])
      roundedcube(54, 54, 20, 3);
  }
  module slot() {
    translate([-5/2,0,washer_h])
      cube([5,23,30]);
  }
  
  difference(){
    outer_body();
    
    // main cylinder to cut out
    translate([0, 0, washer_h])
      cylinder(h=100, r=38/2, center=false, $fn=200);
    
    // washer cut out
    translate([0, 0, -1])
      scale([1, 1, 10])
        washer();
      
    // number slots cut outs
    for (i=[0,2])
      rotate(-14+i*14)
        slot();
    // letter slots cut outs
    for (i=[0:7])
      rotate(82+i*28)
        slot();
  }
}

// ---------- inner part ---------- //
module inner() {
  module inner_body() {
    // main part
    cylinder(h=20-washer_h, r=38/2-0.3, center=false, $fn=200);
    // handle
    cylinder(h=20-washer_h+8, d=9, center=false, $fn=200);
    // sticking out part
    rotate(-14) translate([-4/2,0,0])
      cube([4,22.5,20-washer_h]);
  }
  
  module puncher_hole() {
    sw=stamp_w+tolerance;
    sd=stamp_d+tolerance;
    rotate(-14) translate([-sw/2,
      (washer_dia+washer_hole)/4-sd/2,
      -10])
      cube([sw,sd,50]);
  }
  
  translate([0, 0, washer_h]) {
    difference() {
      inner_body();
      puncher_hole();
    }
  } 
}
outer();
translate([70,0,0])
  inner();

A note on material choice:

When you are talking about extreme weather conditions, I don't know if you know this but 304 stainless steel can easily be corrupted if exposed to salt water, so if you are living in area near sea water I would opt out for better 316 stainless steel.
I am not sure if Jameson Lopp did any tests with salt water, but I believe that is much more realistic threat for some parts of the world compared to acid exposure.

Not all stainless steel is made the same, there are different types and grades, so while 316 SS is better for salt water it does have slightly lower melting point compared to 304 SS:

Grade 304 melting points: 1400-1450°C (2552-2642°F)
Grade 316 melting points: 1375-1400°C (2507-2552°F)
Grade 430 melting points: 1425-1510°C (2597-2750°F)
Grade 434 melting points: 1426-1510°C (2600-2750°F)
Grade 410 melting points: 1480-1530°C (2696-2786°F)
Grade 420 melting points: 1450-1510°C (2642-2750°F)

Pick 304 if you want high temperature resistance, or pick 316 if you want high corrosion resistance.

[o_e_l_e_o]

This is very cool. Great project!

Remember to also stamp on the position number of each word in your seed phrase. The last thing you want is to drop the whole thing when trying to recover your seed phrase and end up with 24 washers on the floor in a random order, which will be impossible to brute force.

In terms of welding the nut on and then cutting it off again - what is the risk that you damage your back up by doing this? I suppose you could always use a longer bolt with some extra washers, so they are still tight and can not be read while the device is sealed, but giving you some dead space between where you are welding/cutting and the washers containing your words.

[n0nce]

This is very cool. Great project!

Remember to also stamp on the position number of each word in your seed phrase. The last thing you want is to drop the whole thing when trying to recover your seed phrase and end up with 24 washers on the floor in a random order, which will be impossible to brute force.

In terms of welding the nut on and then cutting it off again - what is the risk that you damage your back up by doing this? I suppose you could always use a longer bolt with some extra washers, so they are still tight and can not be read while the device is sealed, but giving you some dead space between where you are welding/cutting and the washers containing your words.

Thanks for your feedback!

Yes, word index is part of the blockmic design and I incorporated it as well (see the 2 notches above the 8 notches - those are for the index)
However I later noticed I should have done a stamp with such a number on it, to display how it will look
I will do it tomorrow if I remember

Dead space for angle grinding sounds good to me!

[SFR10]

(tape holds washer in place)

Before starting the hammering, the mold that I have created has a small defect that I have not really been able to correct without adding anything external. And it is that when hammering the first character and extracting the moving part to do it in the second, the washer moves and the final result is quite bad. To fix this I use a little electrical tape, making the result look good by not moving the washer during the whole process.

Have you tried stamping it without any tape? I'm curious to know how it moves? Does it turn or it comes out slightly when you remove the moving part?
^{- Depending on the answer, I could help in finding a solution for each, but it would probably require modifying almost everything [if you want, I can provide the STL file on Monday (assuming that you still have some old filaments to spare)].}

[n0nce]

(tape holds washer in place)

Before starting the hammering, the mold that I have created has a small defect that I have not really been able to correct without adding anything external. And it is that when hammering the first character and extracting the moving part to do it in the second, the washer moves and the final result is quite bad. To fix this I use a little electrical tape, making the result look good by not moving the washer during the whole process.

Have you tried stamping it without any tape? I'm curious to know how it moves? Does it turn or it comes out slightly when you remove the moving part?
^{- Depending on the answer, I could help in finding a solution for each, but it would probably require modifying almost everything [if you want, I can provide the STL file on Monday (assuming that you still have some old filaments to spare)].}

Yes, I tried without tape as well. Due to the good friction fit, it doesn't come out, but it can move a little. At least in my version, that is. Had no way of trying the blockmit so far
So in theory, it would work without tape, as long as you don't need to punch a letter twice often. Because sometimes it rotates just a slight bit.

But it's really not a big issue in my opinion with the tape; quite easy with normal packing tape or wide transparent tape
I'd be glad to hear any recommendation / improvement suggestions though!

I was already thinking of modifying the file so that you can screw the jig into a piece of metal beam, but then it would be tedious to get the washer out and to replace the tape when needed. I don't really see another way to hold a round object in place other than friction to be honest.

[SFR10]

Because sometimes it rotates just a slight bit.

But it's really not a big issue in my opinion with the tape; quite easy with normal packing tape or wide transparent tape
I'd be glad to hear any recommendation / improvement suggestions though!
~Snipped~
I don't really see another way to hold a round object in place other than friction to be honest.

You're right... I wanted to tackle that issue by using "square washers" instead ^{[I do know it's probably not worth the trouble to modify everything in order to integrate a different shape into the design, but it'll solve that problem completely]}.
^{Note: I'm not vouching for the website that I've included as an example.}

[o_e_l_e_o]

I don't really see another way to hold a round object in place other than friction to be honest.

It would be a significant amount of additional work for very marginal gains, but you could cut a small wedge out of each washer and modify your jig design so there is a small piece which sticks out in to the wedge cut-out to hold the washer in place. Almost certainly not worth the time, though. Your other option would be to buy square or other non-round washers, but again, you would obviously need to redesign your whole jig.

It sounds like your set up works fine with tape though. If you really mess up a washer by trying to punch it twice and being out of alignment, then you can just make a new one - it's not like you've messed up the entire back up as you might have done with a single steel plate.

[n0nce]

I wanted to tackle that issue by using "square washers" instead ^{[I do know it's probably not worth the trouble to modify everything in order to integrate a different shape into the design, but it'll solve that problem completely]}.
^{Note: I'm not vouching for the website that I've included as an example.}

I didn't know these existed, but it seems an option as well! In general the cool thing about these products is that the price / weight of stainless steel is so so cheap. I don't think they would stay on a screw as nicely as round washers, but it would be doable. When I'll find time to sit at the CAD again, I might give it a shot, though I don't have such washers here to try / experiment with.

I don't really see another way to hold a round object in place other than friction to be honest.

It would be a significant amount of additional work for very marginal gains, but you could cut a small wedge out of each washer and modify your jig design so there is a small piece which sticks out in to the wedge cut-out to hold the washer in place. Almost certainly not worth the time, though. Your other option would be to buy square or other non-round washers, but again, you would obviously need to redesign your whole jig.

It sounds like your set up works fine with tape though. If you really mess up a washer by trying to punch it twice and being out of alignment, then you can just make a new one - it's not like you've messed up the entire back up as you might have done with a single steel plate.

I agree; the gain is small and it's really easy to put a piece of tape there. Or not, but then maybe only stamp a letter once. Modifying the round washers in any way will 100% take more time than using tape. One idea would be to drill a small hole into the washers using an appropriate hole in the jig to make it square and to use it to keep the washer aligned afterwards. But I think everything we can come up with is more involved than a piece of tape (it can be reused after each washer).

I'm not even sure how the suggestion of using some tape is such a big concern to be honest For me, after reading the BlockMit article, it was a no-brainer to just keep that concept since it seemed so easy and quick to do anyway.

As you said, it's great that each word has its own washer with costs just a few pennies, so even if a letter comes crooked due to omitting tape, just take another washer. I have to say; I never had such a good looking steel backup..

I know, you can create a jig for a steel plate backup as well, but if you still mess up, you will need a new $20 plate.

[LoyceV]

An idea to achieve tamper evidence and protection (though we had the discussion if it's even a good idea or not): weld on the nut.

What about rust? I know that's usually not a problem with washers I've had laying around forever, but if it holds crucial information, I wouldn't mind oiling them before bolting them together. Especially since this won't be in a normal drawer but probably somewhere well hidden.

Protection: Not everyone just has an angle grinder.

I can just imagine myself getting my angle grinder to buy something

I don't really see another way to hold a round object in place other than friction to be honest.

Have you considered a magnet? They're available in many sizes and shapes on AliExpress and can probably fit somewhere inside the 3D design. Unless you're going for stainless steel washers, but I assume those are too hard to stamp.

[dkbit98]

I prefer to customise it for you and sell you a print or printable file

Cool project and I think I saw similar thing recently when I wrote about metal seed backups.
I see you written nice Bitcoin Talk, so do you have your own stamping tools and letters or you borrowed it?

What about rust? I know that's usually not a problem with washers I've had laying around forever, but if it holds crucial information, I wouldn't mind oiling them before bolting them together. Especially since this won't be in a normal drawer but probably somewhere well hidden.

They are stainless steel washers, rostfrei, meaning free from rust, but it is possible to develop some rust during long periods of time, under special conditions or if weaker alloy is used.
I think that painting would be a better protection solution than oiling them.

[n0nce]

An idea to achieve tamper evidence and protection (though we had the discussion if it's even a good idea or not): weld on the nut.

What about rust? I know that's usually not a problem with washers I've had laying around forever, but if it holds crucial information, I wouldn't mind oiling them before bolting them together. Especially since this won't be in a normal drawer but probably somewhere well hidden.

Yes, for sure, protecting the material should be taken into consideration, but it depends on the washers' metal type, so I provided no information so far about that. I am under the assumption that mine are stainless steel, however after reading your suggestion, I tried to see if they're magnetic and they are, just a bit.

Protection: Not everyone just has an angle grinder.

I can just imagine myself getting my angle grinder to buy something

That's how we roll! Bring your battery powered grinder to the store

I don't really see another way to hold a round object in place other than friction to be honest.

Have you considered a magnet? They're available in many sizes and shapes on AliExpress and can probably fit somewhere inside the 3D design. Unless you're going for stainless steel washers, but I assume those are too hard to stamp.

I am pretty sure mine are stainless steel, similarly to many commercial 'steel backups', which is quite good for backups. Stainless steel can be magnetic and I had not thought about using magnets so far, great idea.
However, the washer has to be held either from the top or the bottom (side is too shallow I think). From the bottom is tricky because then you'd be hammering onto the magnet, not sure if they're made to withstand that. From the top won't work, because the top is not covered by the 'outside' part of the jig, instead by the (removable) inside. We need a way to stick the washer to the outside part instead.

I have one idea which would require re-seating the washer for applying the numbers though, since I'd put a magnet in that location roughly. So you would need to do the number first, rotate the washer by 180 degrees and then do the words.

I prefer to customise it for you and sell you a print or printable file

Cool project and I think I saw similar thing recently when I wrote about metal seed backups.
I see you written nice Bitcoin Talk, so do you have your own stamping tools and letters or you borrowed it?

Thanks for the feedback! I mentioned where I found the idea in the starter post; it's not mine. As far as I know, the BlockMit guys are the ones who came up with it. I just recreated a new jig in Fusion with parametric values for everything, compared to their Tinkercad model that was hard to modify.

The tools I used were 2 hammers and normal 6mm high letter stamps! I got them when I made my first steel backup for around 30€ with all numbers and letters.
2 hammers? I don't have an anvil, but a washer is so small it can fit on the side of a larger hammer. This way you don't need to hit them as hard as when using a wooden workbench as support, since that absorbs a ton of energy.

My stamps are from 'Gravurem': https://www.heidenpeter.de/en/products/handschlagstempelsaetze/gravurems-standard/
At least in the 6mm variant, the tip is a bit taller than the bit's actual size, so I created the jig with this in mind. So the stamp is inserted into the inner circle 'from below'. But in case your stamps are equal sized from top to bottom, I will adapt the file to reflect that geometry.

Edit: Ordered some magnets, will try something that would require no tape, once they arrive

[n0nce]

Small update: After doing a few backups, unfortunately it is indeed pretty tedious to use tape, since it has to be replaced frequently. By the washer being hammered into the underlying metal support, it damages the tape around its perimeter and it's hard to remove & reuse it without ripping.

5mm diameter neodymium magnets however don't hold the washer in place too well; I will maybe need stronger / larger ones to get a satisfying result. Will update when I got something new; maybe simply stronger tape would help as well (ran out of electrical tape).

I suspect the bad performance of the magnets is due to low ferrite content in the metal, so especially if you find very 'good' stainless steel, magnets won't work.

[LoyceV]

How about a more classic way to hold the washer in place: a screw
Drill a hole from the side, taper inner thread, put a screw in it.

One pointy screw at the right place should keep it in place:


Even better if you can tighten it by hand:


Disclaimer: I have no idea how strong 3D-printed plastic is.

[SFR10]

unfortunately it is indeed pretty tedious to use tape, since it has to be replaced frequently.

How about a more classic way to hold the washer in place: a screw

LoyceV's comment reminded me of something that would defeat the purpose of printing the jig part: Clamps ^{[it'd require covering 1/3rd of the washers]}

• Off the top of my head, I can only name a few out of the hundred clamp types, so I'd suggest using a "G-clamp" or an "in-line clamp" for holding the washers in place ^{[if you have one]}.
  ^{Note: There might be better clamp types than the ones I've mentioned above.}
  
  • If you don't have or can't find one, you can 3D print them as well ^{[e.g. G-Clamp fully printable]}.

Out of curiosity, do you have a CNC machine ^{[apart from the 3D printer]}?
^{- If you do, then just use its clamps.}

[n0nce]

How about a more classic way to hold the washer in place: a screw
Drill a hole from the side, taper inner thread, put a screw in it.

You sir, are a genius! To be continued...

Disclaimer: I have no idea how strong 3D-printed plastic is.

You can screw directly into a slightly undersized hold and it holds very well, it's also possible to insert heat-fitted inserts. Both are about equally as strong last I checked

unfortunately it is indeed pretty tedious to use tape, since it has to be replaced frequently.

How about a more classic way to hold the washer in place: a screw

LoyceV's comment reminded me of something that would defeat the purpose of printing the jig part: Clamps ^{[it'd require covering 1/3rd of the washers]}

I don't think the main purpose of the jig is to hold the washer in place. Otherwise, of course a clamp would do a good job easily. The 2 main factors over not using a jig (after some experience with steel plates and no jigs): the letters come out well almost 100% of the time, since jig holds the bit perfectly perpendicular and you can re-stamp in the exact same location. Secondly, the jig helps you align the rotation and spacing between letters. So no letter ends up tilted to one side or way too close to another.

[SFR10]

I don't think the main purpose of the jig is to hold the washer in place. Otherwise, of course a clamp would do a good job easily.

I forgot to add "to an extent" when I said it'd defeat the purpose of printing it ^{[my bad]}.

since jig holds the bit perfectly perpendicular and you can re-stamp in the exact same location.

You have a point but you can still get good results without the jig ^{[or a tool bit boring bar and a holder]}, provided that you don't have a hand & arm tremor and as for the re-stamping part ^[CMIIW], I don't think there's a need for one if you hit it three to four times with enough force ^{[in quick succession]}.

Secondly, the jig helps you align the rotation and spacing between letters. So no letter ends up tilted to one side or way too close to another.

Since the majority of the letter stamps, come with right-angled ^{[or squarish]} shafts, then with a proper technique you can still get almost perfect results in round shape washers...

• This should be the view from the top:
  
  

There's no doubt that the "Blockmit jig" is a great product, but you can still achieve good results without having one!

[n0nce]

I don't think the main purpose of the jig is to hold the washer in place. Otherwise, of course a clamp would do a good job easily.

I forgot to add "to an extent" when I said it'd defeat the purpose of printing it ^{[my bad]}.

All good!

since jig holds the bit perfectly perpendicular and you can re-stamp in the exact same location.

You have a point but you can still get good results without the jig ^{[or a tool bit boring bar and a holder]}, provided that you don't have a hand & arm tremor and as for the re-stamping part ^[CMIIW], I don't think there's a need for one if you hit it three to four times with enough force ^{[in quick succession]}.

Heheh, you have a point there. No tremor on my side, but I have to confess I am not the most proficient 'hammer-er'. It's probably simply due to me overall preferring screws and almost everything I build is made of screws instead of nails. So the jig definitely helps to get every letter perpendicular and straight. I did a few steel backups in the past and the letters always came out bad, not nearly as good as on these washers with this jig. And I didn't hurt any finger even once!

Secondly, the jig helps you align the rotation and spacing between letters. So no letter ends up tilted to one side or way too close to another.

Since the majority of the letter stamps, come with right-angled ^{[or squarish]} shafts, then with a proper technique you can still get almost perfect results in round shape washers...

I appreciate the sketch, but I am not sure I understand it except of 'well, align it with the edges of the washer', or am I missing something?

There's no doubt that the "Blockmit jig" is a great product, but you can still achieve good results without having one!

For sure, I guess it depends on technique / experience.

[SFR10]

And I didn't hurt any finger even once!

That should also be one of the main reasons for using a Blockmit jig

I appreciate the sketch, but I am not sure I understand it except of 'well, align it with the edges of the washer', or am I missing something?

Sorry, I should've been clearer but I believe you got it right ^{[e.g. no uneven sides when you check the spaces from the top]}.

[fillippone]

Awesome!
I stumbled on this thread almost by chance and this is definitely something I would like to test in the near future.
Low tech, durable way, of storing bitcoin is definitely something I would like to test.

I already had a tough on the topic,

Gifting satoshis to future generations

Now, trying first hand is now on my 2022 project list.